Cross-correlation of multiplicative and additive noises in a single-mode laser white-gain-noise model and correlated noises induced transitions

We examine the mechanisms of cross-correlation of white multiplicative noise and white additive noise in a single-mode laser and establish a white-gain-noise model containing such a cross-correlation. We show that the cross-correlation between the white multiplicative noise and the white additive noise causes the phase of the laser field being locked at a fixed value, in contrast to that the phase diffuses freely when the cross-correlation is zero. Consequently, the laser intensity becomes decoupled from the phase and a closed form of Langevin equation is obtained for the intensity. Studying the steady intensity distribution, we find a new phase and re-entrant phase transition that were absent in the white-gain-noise model without cross-correlation. (C) 1999 Published by Elsevier Science B.V. All rights reserved.